Telephone system



Dec. 28 1926.

D. B. ROBISON TELEPHONE SYSTEM Filed Sept. 29. 1923 ldatented lec. 28, 1926..

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IDANlEL B. BGBSON, OFCCERO, ILLNGIS, SSIGNOEL TO KELLOGG SWITCEIBOARD ANI) SUPPLY COMPANY, OF CHCAGO, LLI'NOIS, A CORFORATIUN 0F ILLN'OIS.

TELEPHONE SYSTEM.

Application filed September 29, 1923.

My invention relates to telephone systems and has to do more particularly to telephone systems ot the intercommunicating type in which each telephone station is provided 5 with lines leading to each of the other stations7 suitable i switching arrangements being also provided whereby any station oi the system may be connected to the line leading to another station or to one or more trunks common to all of the stations and leading to a distant central oiiice or main exchange.

in systems of this general character the attendant at the station that receives the incoming calls from the main exchange in addition to the usual key equipment is provided with additional key means for holding the connection between the main exchange and the party at the station of the intercomf' municating system and this additional key means also controls the supervisory apparatus at the main exchange so that upon the termination ot conversation the key means is actuated to operate the supervisory apparatus to give the operator at the main eX- change a disconnect signal. This additional key means at the attendants station 'further complicates a system ot this character and to overcome this olojectional feature l ffl eliminate these additional keys associated with the attendants station and provide the station with the key equipment similar to the other stations and in place of which l provide relay means tor accomplishing the saine rcsnlt which is entirely automatic.

A. feature of iny invention is the provision of a holding relay for each incoming trunk, the. said relay of a trunk being operated when the attendant removes his receivor in response to a call from the main exchange to cont-rol the supervisory apparatus thereat. This holding relay remains cncrgi; .i daring he "i ie that the attendant is extending the con oction to the called party and upon completion ot the connection the act oit replacing the receiver at the attendant station, the relay is cle-energized and cut out of the Circuit thus placing the cintre-l of the supervisory apparatus of the main exchange under the sole control of the called party.

Another feature oi' my invention is the provision ot a signal tor apprising the at tendant that a call from a main exchange is i5 awaiting his attention, and this signal in Serial No. 665,519.

addition to serving as a call signal also serves as a holding coil to hold the control of the supervisory apparatus at the main exchange under the control of the intercoinmunicating branch during the time that the attendant is extending the connection to the called party.

For a more complete understanding of my invention reference may he had to the accompanying drawing and referring nowyin general to my invention as illustrated in the accompanying drawing l show for the purpose ot illustration three stations associated with the intercoinniunicating system of my invention. Stat-ions A, B and AT are of a well known type comprising the usual substation equipmentincluding, a receiver and its associated switchhook.I transmitter, call bell and induction coil.

The substations A, B and AT in addition to carrying on the usual conversation between stations are also adapted to be connected to a main exchange. As is well known in a system ot this type the stations connected thereto are scattered 'throughout the building in which the system is located and it is of course necessary to have one station of the system receive the incoming calls from the main exchange. For the purpose of illustration I have shown the station AT as the attend ants station and all the incoming calls will be answered hy him and extended to the station wanted. Each station ot the system is equipped with a group of keys by means of which the stations may loe interconnected and are of the well known locking type whereby upon depressing any key, the depressed key is locked in its depressed position and any key having heen previously operated being at the saine time released for the purpose ot interconnecting itself with any other station ot the system, and for eX- tending itself over a trunk to the main exchange.

The station A isprovided with a hoine or lo al answering key HAK which the party thereat will actuate when called toeconnect his station with the station calling. v Keys BK andATl are'also provided the keygBl bei-ng multiply connected with lkeys BK, associated with the other stations-and @the home or local answering key HBK associated with the station B so that any station` ol the system `may connect itself withstation B. The key ATB; is multiply connected invention may now be with the keys ATK associated Wit-h the other stations and the home key or local answering HTK of station AT so that any station oli' the system may connect itselI with station AT and vice versa. A ringing key Eli: which is of the non-locking` type is provided Which depressed by the party at station A when signalling anyT other station oi the system. Trunk keys TKA and TKB are also provided with lead to the trunks T and T at the inain exchange over their re spec-tive trunk conductors 2, and d, 5 Wherelfy the station .fr may extend a call to the niain exchange or receive call from the main exchange.

The station E is provided with a honie or local answering HBK key ior purposes as already described and in addition. is provided with a key lli which is multiply connected with the keys Al associated with the other stat-ions and the home or local answering` key reali". oi' station so that any station of the systein may connect itself with the station Tae key ATH associated with the substation is provided tor purposes as already described in connection with station A, ring key Pili and trunk keys TKA and TKB are also provided tor purposes as above described. The station AT is provided with a heine or local answering key HTK and in addition is provieed with a l-ey Al Vand DE". a. ringing key RK2 and trunk keys Tril@ ttor the purposes as above described.

The trunks T and T leading from the interconiinunicating systeni TC terminate at the main exchange X which l have slioivn to the right of the dotted line into line circuits L and L which comprise respectively line rela-y LB and LR', line .signals S and S', jacks J and fl and cut oli relays COand e The trunks T and T at l() are. also provided with holding relay HR and HR for purposes as Will presently be described. Call signals CS and CS at IC in the torni ofthe usual call signal bells are ass ciated respectively with trunks T and T and are actuated when a call is extender troni the rnain exchange to signal the attendant at TC, I provide a source olf' ringing` current battery RB for operating;- the call bells at the stations the said battery also serving to operate certain supe 1visory equipment tor purposes as will presently be described. Talking battery TB is also provided for supplyingr talking current to the tion coils RC, RC and With the general description in inind the fully undfnstood troni a description ot the operation. Assuming that the party at the station l desires to call the station E. the party at station A. removes his receiver rrorn its switchhool: and fully denresses the key BK which key is multiply connected to the stations to close its spring stations through retarcat contacts 6, 7 and 8, 9 to bridge his telephone set across line conductors l0 and l1 troni the station terminal l2 over conductor 13, closed contacts 6 and 7 of the key Bl to the conductor lO, the other station lead extending from terininal ll over conductor l5, through closed contacts 8 and 9 of the key BK to the line ll. The party at the station A novv depresses the. ringing key RK to connect ringing current to the call bell of the station B the ringing circuit inay now be traced troni one side battery RB over conductor 16 conductor l?, normally closed contact 18 of the switchhook of the station telephone lil, the call bell 19', conductors 2O and l0, closed contacts ti and 7 oit the key Bl, conductor lill. closed contacts 2l and 22 of the depressed ringing key RK, conductor 23 to the other side of battery RB. The call bell i9 at station B is actuated each time the ringing key RK is depressed by the party at the tion The party at the station B in response to the signal thus given from his call bell i9 reinoves his receiver troni its svvitclr hook open Contact 18 to open the ringing current circuit through the call bell 19. T he party at station B now depresses the home or local answering key ,ll-TEK and the closure ot contacts l, 25 and Q6, 27 will bridge his telephone set to the line conductors l() and il from the station termina-l 28 over conductor 29 through the closed contacts Qil and 25 ot the key HBK to the conductor 10, the other telephone lead extending troni the station terminal 30 over conductor 3l through closed contacts 26 and 27 of the key HBK to conducitor ll. The part-ies at stations A and now have their telephone sets bridged across the line conductors l0 and ll and inay new carry on a conversation, talking' current tor the stations A and B is supplied troni talking' battery TB through the retardation coil BC and upon the termination o the conversation they replace their receivers upon their respective sivitchhooks.

lt the party at station A Wishes to conii1iur...icaIlle with the party the stati-on T ,Wr at the station A., will be :tully depressed and release any key that nir-y be in a locked position and the closure of contacts 32. and 3l and 35 ot the key it@ rrill bridge the telephone set of the station to line conductors 36 and 37. rThe pa the statici A now depresses the ringing RK closing circuit :tor ringing curr the call bell 38 at substation ifs/,T v be traced troni one of battery conductors 16 c1 sed Contact d() of the sivitchhook at the t AT., call boli 3S, conductor el, conducts?? closed contacts 32 and 33 of the key conductor 13. closed contacts 2li and ot ringing key RK to the other side of the battery RB over the conductor AThe party at the substation AT in response to the call CFI -nere signal removes his receiver troni the swittihhook and presses his honie or loca-l answering hey HTH loca-ted at the substation AT and 'the closure ot' contacts 42, 43 and del, l5 will bridge the telephone set ot the station AT to the line conductors 86 and 37 and the parties at the stations A and AT, now have their telephone sets bridged across line conductors 38 and 3'? and inay now carry on a conversation. Battery for talking purposes extends troni the talking battery TB through the retardation coil RC to thev line concluetors 3G and 37 and supplies 'the station A and i-iT With battery for talking purposes.

Assuming that the party at the station A desires to obtain access to the central. oli'ce or inain exchange over the trunk T the trunl: key Tlii associated with the trunk T located `at the station A. is depressed thereby bridging the telephone set of the station A. over conductors 13 and l5 through the closed contacts 46, 417 and- 483 19 of the depressed trunlr lrey Tli; to the trunk' conductors 2 and 3 of the trunk T which terminates the central oliice or inain exchange X into the line circuit L, the removal` of the receiver at the station A closes an energizing circuit for the line relay LR at the niain exchange X troni battery through the Winding el? the relay LR norinal" Contact oi the cut oil" relay C@ trunk conductorl 3 through the closed contacts 48 and of the trunkkey TKA, conductor l5 through the now closed contacts at the station switchhoolr conductor 13 through the closed Contact lo and 45? ot the key TKA trunk conductor 2 to ground at norinal contact 5l ot the cut ol'l' relay C() at the niain exchange. The closure of alternate contact 52 of theline relay LR closes a circuit through the line lamp or signal S, to apprise the operator at the Inain exchange that a connection is desired. The operator at the niain exchange in response to the lighted signal S inserts an answering plug of a cord circuit into the jack J associated With the trunk T to establish an energizing circuit of the cut oft" relay C() and upon listening iind that this t-rnnlr is busy the party at station will then' depress the trunk hey TKB and the closure of contacts 53. 54. and 55 56 ol.3 the trunk TKB will now bridge the telephone set ot station A to the trunk conductors 4, 5 of trunk T whichV terminates at the ,central olice or main enchan X to line circuit L. The stations l-l and AT oi the interconnnunicating set TC are also provided with trunk keys TKA and TKB and TKL and Tlllg spectiyely and by depressing thel respect-ire keys may connect themselves with the niain exchange X over trunk conductors 2 and 3 or eland 5 of the trunls T or T.

lf a call cornesl in over the trunl; T arsociated with line circuit L troni the central oliice for the station ringing current troni the n'iain exchange will flow from the tip Contact of the jack J through alternate contact 51 to the cut off relay C@ which relay is energized When connection is made to the jack J of line circuit L through the cali signal CS located at the attendants station AT through the condenser 59 back through alternate contact 5() to the sleeve con'tact'oi" the jaclr J and to the source of ringing current at thecentral oni-ce. The attendant at. station AT Who answers all incoming calls troni the ina-in exchange as previously d escribed rernoyeshis receiver troni the switchhoolr in response to the signal GS and depressesthe trunk key TKA2 which is niultiply associated With the trunk T over which the call from the main exchange has been extended to close its contacts 61,62 and 63, 6e and the closing of the nornially open switch hook contacts at the station AT establishes an energizing circuit through the lower Winding SO of the holding relay HR associated with' the trunk T from battery at the' ina-in exchange through the sleeve of the jack J alternate contact 50 ot the cut on relay CO' over the trunk conductor 3 closed contacts 63' and 64k of the depressed trunk lrey TKA`2 associated with the station AT conductor 65 through the Winding 60 of the holding relay HRg conductor 66 through the closedA contacts of the switchhool at the station AT bach over conductor 67 through the closed contact (i2 and Gl of the depressed trunk key TKAZ over the trunk conductor 2 through alterna-.te contact 5l oit the cut oii1 relay CO of the trunk T tothe tip contact of the jack J associated with the trunk T to ground or other side of battery at the main exchange. The circuit just traced through the lower Winding 60 ot the holdin-g relay HR of trunk T controls the operation of the supervisory apparatus at the main exchange X is Wellunderstood. The energization of relay HR closes a locking circuit tor itself as will be hereinafter described.

The attendant at the station ,XT being y apprised of the tact that the party at the station A 'is wanted non' depressesfthe key AK associated With the station and inuitiply connected with the station its The key AK upon.heingdepres'ed releases the depressed trunk key Tlrii2 and the opening otcontacts 6l, G2 and 68,- (Sel of the said key opening the cireuitthrough the `loii'ruf at the station .L

Winding ot the holding relay HR but the relay HR does not cle-energize as the closing,l ot alternate contact l0 oi the switch hook when the saine Was raised upon the removal o1a the receiver and upon the operation of relay HR established a lockingcircuit through the upper Winding oi' relay HR Which circuit may be traced from one side of the battery RB over conductors 16 and 39 through alternate contact Ll() ot the switchhook contact, conductor 71 through the Winding 70 ot the holdino' relay ETR, its alternate contact 72 over conductor 73 to the other side ot battery RB. The holding; relay HR is thus held energized. The closure oi its alternate contact Til permitted the circuit oi' the supervisory apparatus ot the cord circuit at the inain exchange to extend through the call signal CS through alternate contact 74 or" the hoine r lay Elli to hold the supervisory apparatus at the main exchange atter the irey TTQV is released. The closure of contacts Z5v` 76Y Ti' and .78 ot the lrey l'i novv bridges the attendants station iT across the line conductors 79 and 80. The attendant at the .station .AT new depresses the ringing' key operate the call signal Sl at the stathe circuit 'for rii ring current to 3" aetuate the called signal 8l at the station A lic-irril raced from one side ot the battery Rl?) over the conductors 1G normal contact S2 ot the switchhook at station A called signal Si. conductor 79 through the closed contact and 76 o'tliey AK conductor 65 through the closed contacts 83 and 84 of the ringing' key BKZ. conductor Q3 to the other side ot battery RB.

The party at the station A in response to the call sigrnal 81 removes his receiver from the sivitchhool: and the opening' or normal contact 82 olf the sivitchhool interrupts the ringing` circuit. The party at the station A nov.7 dcpresses the home or local answering lreyV HAK associated With the station A. and the closure oi contacts 90. 91 and 99., 93 oi' the hey HAK bridges the telephone set ot the station to the line conductors 79 and S0. The party at the station A. and the attendant at the station AT are nou'v in conversation over circuit ot the. lin-e conductor 79 and 80. The attendant at the station AT non' informs the party at st.- tion A that a call from the main exchange is Waiting; his attention and also assigns the trunlr which is to be used by the party Hari assumed that the call i'roin the main enc ianjeje has been extended over th trunk T. the attendant at the station. AT informed the parti' at the station to depress the trunk hey TKA and when the lrey TKA is depressed the closure ot its contacts 16. i7 and 4S. t9 bridges the telephone set ot the station A over the trunk conductors 2 and 3 of the trunk T with the main exchange conductors through the inediuin of the jack J of the line circuit L and the plug` of the cord circuit at the main ei;- change. The attendant at the station AT atter listening and linding` that the party at the station A is connected and talking to the calling party at the main exchange new replaces his receiver upon the sivitchhook and the opening of alternate contact l0 of the switchhook opens the locking circuit ot the holding relay HR through its Winding' 70 and the relay HR restores and as trunk conductors 2 and 3 of the trunk T are connected to the tip and sleeve conductors ot the line circuit L, the party at the station fr now controls supervisory apparatus at the main exchange. Upon completion ot conversation, the party at the station A replaces his receiver and the opening ct the switch hook contacts thereat, operates supervisory apparatus at the main exchange notifying the operator that sup rvised the connection that the party at station A has replaced his receiver and the disconnection from the line circuit L by the Operator is brought about. Should a call be extended i'roin the main exchange through the line circuit L which leads to the trunk T, the call signal CS associated With the trunk T is operated and the attendant at the station AT moves his receiver and depresses a trunk key TKB2 to connect his telephone set with the trunk T and the operation of the system TC for extending the connection trom the main exchange over the trunk T to any of the parties ot the intercommunicating system IC is readily understood from the previous description in Which call trom the main exchange has been extended to the station A.

Vhile l have shown the station AT as the attendant station it is readily apparent that I may select any of the stations ot the system IC as the attendant station by the simple adding ot the alternate Contact to the sivitchhook contact as illustrated in connection with the station AT. Tt may be seen that by the arrangement above described, various stations ot an intercominunicating system may bel connected by means ot the keys and all the stations of the system may also extend calls to the main exchange by means ot the trunk keys Without the aid ot an attendant. The stations of the system l@ may also receive calls troni the main exchange and after the attendant has apprised the party of the tact that a call. from the main exchange is awaiting/j his attention he may again replace his receiver upon the svviteh hoolr and automatically disconnect himself from the connection and place control of the superif'isory apparatus at the main exchange under the sole control ot" the station that is connected.

lt may also be seen that l have eliminated Leidos? all additional keys at the attendants station and place the control ot the supervisory apparatus under his control during the time that he is extending the connection to the called party and the replacing of his receiver disconnects his station from the connection and places the control of disconnection under the sole control of the called party.

While l have illustrated and described a preferred embodiment of my invention, it will be understood that it may be embodied in many Widely different organizations and l therefore do not Wish to be limited to the exact system shown and described but aim to cover all such changes and modiiications as come Within the spirit and scope of the appended claims.

What- I claim as new and desire to secure by United States Letters Patent, is as follows:

l. An interccmmunicating system et the character described comprising a plurality of stations, a trunk circuit multipled to the stations, a telephone set at each station adapted to be connected with said trunk circuit, a trunk key and a relay associated With said trunk circuit, said telephone set being connected to said trunk When said trunk key is actuated, an energizing circuit for said relay upon connection of said set and actuation ot said trunk key, and means controlled by said relay :tor maintaining the continuity ot said trunk until another said trunk key and set is connected thereto.

2. An intercommunicating system of the character described comprising a plurality ot' stations, a trunk circuit multipled to the stations, a telephone set at each station adapted to be connected with said trunk circuit, a trunk key and a relay associated with said trunk circuit, said telephone set being connected to said trunk when said trunk key is actuated, an energizing circuit for said relay upon connection of said set to said trunk and upon actuation ot' said trunk key, and a bridge for maintaining` the continuity ot said trunk circuit in substitution of said set.

3. ein intercommunicating system ot' the character described comprising a plurality of stations, a trunk circuit multipled to said stations, a trunk key, a telephone set at each station adapted to be connected with said trunk upon actuation of said trunk key, a relay associated with said trunk energized when said telephone set is connected to said trunk by said key, a bridge for maintaining` the continuity ot said trunk in substitution of said set and switching means controlled by said relay for controlling` said substitution.

l. An intercommunicating system of the character described comprising a plurality of stations, a trunk circuit multipled to said stations, a trunk key, a telephone set at each station adapted to 'be connected with said trunk upon the actuation ot' said trunk key, a relay associated with said trunk energized when said telephone set is connected to said trunk by said key, a locking circuit for said relay controlled by said telephone set, and a substitute bridge for said trunk controlled by said relay for maintaining the continuity of said trunk in substitution of said set.

5. Ain intercommunicating system of the character' described comprising a plurality ot stations, a trunk circuit multipled to said stations, a trunk key, a telephone set at each station, a relay, an. energizing circuit tor said relay controlled by said trunk key and one ot' said telephone sets, a locking circuit for said relay controlled by said telephone set, and a bridge for maintaining the continuity ot' said trunk in substitution of said set.

An intercommunieating system of the character described comprising a plurality of stations, a trunk circuit multipled to said stations, a trunk key, a telephone set at each station, a relay, an energizing circuit for said relay controlled by said trunk key and one of said telephone sets, a bridge for maintaining the continuity ot said trunk in substitution of said set controlled by switching means ot' said relay, and a locking circuit for said relay controlled by said telephone set.

7. An intercommunicating system ot' the character described comprising a plurality of stations, a trunk circuit multipled to said stations, a trunk key, a telephone set at each station, a relay associated with said trunk, connection means controlled by said trunk key and one ot said telephone sets for connecting said one ot said sets to said trunk. an energizing circuit for said relay controlled by said trunk rey and said one ot said telephone sets and a bridge for maintaining the continuity oi' said trunk in substitution of said set.

8. An intercommunica-ting system of the characterdescribed, comprising a plurality of stations, a trunk circuit multipled to said stations, a trunk key, a telephone set at each station, a rela-y associated with said trunk, connection means controlled by said trunk key and one of said telephone sets for connecting said one et said sets to said trunk, an energizing circuit for said relay con trolled by said trunk key and said one oi said telephone sets, a bridge for maintaining the continuity oi said trunk in substitutionof said set, and switching means et said relay for controlling said substitution.

Signed by me at Chicago, in the county ot Cook and State of Illinois, this 19th day ol: September, 1923.`

DANEL B. ROBISON.

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